UITextField 监控输入 textFieldDidCha

首先添加事件

UIControlEventEditingChanged

[self.textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

实现textFieldDidChange:
Singleton为自定义方法

- (void)textFieldDidChange:(UITextField *)textField
{
    UITextRange * selectedRange = textField.markedTextRange;

    if(selectedRange == nil || selectedRange.empty){

      //这里取到textfielf.text最后的值 进行检索

      OutLog(@"selectedRange textField.text [%@]", textField.text);

       NSString *text = textField.text;

       if ([Singleton isEmptyOrNil:text]) {
          // text is empty
       }
       else {

          // do search or other
       }
    }
}